There are many factors to consider: Will you be solo daysailing most often, or cruising with heavy gear and a crew? How strong are the winds you'll most often be sailing in? Do you like to feel on the ragged edge, or well under control? Will you be happy switching to oars or an outboard when the wind goes light? Will you be physically comfortable setting and striking a large lugsail in breezy conditions? What are your attitudes about reefing?

Those are just a few examples. The best you can do is make an educated guess based on how you want to use the boat.